1. Field of the Invention
The present invention relates generally to semiconductor wafer and compact disc manufacturing, and more particularly to a system and method for supplying photoresist or other similar processing fluid.
2. Description of the Related Art
In the fabrication of semiconductor wafers, photolithography processes are used to create patterns on a wafer surface. A critical process in wafer fabrication, photolithography generally determines the surface dimensions of the fabricated circuits and circuit structures. As integrated circuits become smaller and the density of transistors on integrated circuit chips increases, the precision of photolithography, and the ability to pattern smaller and smaller features, gains increasing importance in the evolution of semiconductor manufacturing.
Generally speaking, the photolithography process includes applying a photoresist to a surface layer of a semiconductor wafer, and then exposing the photoresist to light through a pattern to transfer the pattern to the photoresist and change the structure and properties in the photoresist in regions corresponding to the pattern. The photoresist is then developed to remove either the photoresist of the pattern or the photoresist around the pattern, according to the type of photoresist used, to define the pattern in photoresist on the surface layer of the wafer. Once the desired photoresist has been developed,  features are defined in the surface layer of the semiconductor wafer in accordance with the pattern by such processes as etching. Typically, photoresist is resistant to chemical etching solutions so that only those areas defined in the surface layer of the semiconductor wafer where the developing of the photoresist has removed the photoresist from the surface layer of the wafer will be etched to define the desired features.
In other technologies, photoresist is also used in optical disc mastering processes. In the fabrication of optical disc masters, a glass, polycarbonate, or other suitable material, substrate is coated with a photoresist. The photoresist-covered disc is then selectively exposed by a mastering laser. After exposure, the disc is treated with a developing solution to remove either the exposed or the non-exposed regions of the photoresist, depending on the type of photoresist used. The developed disc with the remaining photoresist forms a physical template of a structure of the disc.
As is known, photoresist is generally a light-sensitive chemical, and the sensitivity is typically to a specific range of light wavelengths. Exposure to light within the range of wavelengths to which the photoresist is sensitive changes the structure and properties of the photoresist. Depending on the type of photoresist used, the change in structure and properties is usually from a soluble condition to an insoluble condition, or from a generally non-soluble structure to a more soluble structure. In either case, the exposed photoresist is developed after exposure, and the developing of the photoresist typically results in the removal of the soluble portion of the photoresist to define the pattern with the remaining, generally insoluble, photoresist.
To define ever smaller, and ever more complex, features in photoresist, the photoresist must be free of contaminates, of a desired viscosity, and of uniform consistency. The size of the wafer or disc to which the photoresist is to be applied is  considered for the desired viscosity of photoresist and for the desired thickness to which the photoresist will be applied. The photoresist must adhere uniformly to the surface of the wafer or disc, and must be distributed evenly and of sufficient thickness to serve as an etch barrier in those regions that remain on the surface of the wafer or disc to define the pattern.
Photoresist is typically applied to a wafer or disc using a spin-chuck or other similar type of apparatus in which the photoresist is deposited to a center region of a wafer or disc which is rotated to distribute the photoresist across the surface of the wafer or disc. The photoresist is commonly dispensed from a nozzle positioned over the surface of the wafer or disc. The photoresist is typically maintained in a storage tank or reservoir, and pumped through the nozzle during application. In such a system, the photoresist is first pumped into a supply reservoir, and then is pumped from the supply reservoir to the dispensing nozzle.
In the typical prior art photoresist supply system as described above, microbubbles can be introduced into the photoresist. Such microbubbles constitute unacceptable contaminants in photoresist. The presence of microbubbles can cause defects in fabricated structures in a plurality of ways including, distorting the pattern to be transferred and fabricated on the surface layer of the wafer or disc by preventing sharp definition of pattern boundaries, failing to provide the necessary etch barrier where required, preventing the photoresist from adhering to the surface layer of the wafer or disc resulting in inadvertent photoresist removal during the developing process, and other such fabrication defects. 
In view of the foregoing, what is needed is a method and system to supply photoresist or other similar material that substantially prevents the formation of microbubbles.